En un elemento constructivo prismático sometido a flexión se generan tensiones normales a la sección transversal, , de sentido opuesto en la zona comprimida y en la zona traccionada, que generan un momento resultante de las tensiones internas que iguala al momento exterior aplicado.

Simple non-deviated flexion

When a prismatic piece is being bent by a bending moment that coincides vector-wise in the direction of one of the main axes of inertia, it is said to be subjected to undeviated bending. If there is also no axial force, the bending is said to be simple, and if the section also has a plane of symmetry perpendicular to the moment, a situation that typically occurs in conventional structures, the normal stress at any point is produced in a beam or a bent element when a bending moment is applied. It can be approximated by the formula from Navier:.

Where M is the applied moment, y is the distance from the centroid (center of gravity of the section) to the fiber considered, and I is the second moment of inertia of the section with respect to the bending axis. For greater practicality, the resisting moment is usually used, calculated as:.

Where is the maximum distance from the center of gravity to the upper chord or the lower chord, depending on whether you want to calculate maximum compressions or tractions.

For pieces symmetrical with respect to the center of gravity, loaded only with forces contained in the plane of symmetry that passes through the center of gravity, the calculation of the maximum stress in absolute value is reduced to the calculation of the quotient:.

Deviated flexion and flexion-torsion

For non-symmetrical parts or parts with deviated bending, the situation is more complicated. In non-symmetrical pieces, for example, the center of shear usually does not coincide with the center of gravity, which causes coupling between bending and torsion, which means that if there is bending, there will simultaneously be torsion and vice versa, which requires computing the torsional moment and the tangential stresses in order to estimate the maximum stress.

In the case of parts with deviated bending, that is, parts with bending in a direction that does not coincide with the main axes of inertia, the stress can be estimated by decomposing the bending moment according to the main axes of inertia. If in addition the center of shear coincides with the center of gravity and the warping of the section can be neglected, we can estimate the maximum stress as:.

Where:.

When there is also torsion "Torsion (engineering)") the warping is not negligible, nor are the reference axes necessarily main axes, the expression of the tension at any generic point is given by:.

Where:.

En un elemento constructivo prismático sometido a flexión se generan tensiones normales a la sección transversal, , de sentido opuesto en la zona comprimida y en la zona traccionada, que generan un momento resultante de las tensiones internas que iguala al momento exterior aplicado.

Simple non-deviated flexion

When a prismatic piece is being bent by a bending moment that coincides vector-wise in the direction of one of the main axes of inertia, it is said to be subjected to undeviated bending. If there is also no axial force, the bending is said to be simple, and if the section also has a plane of symmetry perpendicular to the moment, a situation that typically occurs in conventional structures, the normal stress at any point is produced in a beam or a bent element when a bending moment is applied. It can be approximated by the formula from Navier:.

Where M is the applied moment, y is the distance from the centroid (center of gravity of the section) to the fiber considered, and I is the second moment of inertia of the section with respect to the bending axis. For greater practicality, the resisting moment is usually used, calculated as:.

Where is the maximum distance from the center of gravity to the upper chord or the lower chord, depending on whether you want to calculate maximum compressions or tractions.

For pieces symmetrical with respect to the center of gravity, loaded only with forces contained in the plane of symmetry that passes through the center of gravity, the calculation of the maximum stress in absolute value is reduced to the calculation of the quotient:.

Deviated flexion and flexion-torsion

For non-symmetrical parts or parts with deviated bending, the situation is more complicated. In non-symmetrical pieces, for example, the center of shear usually does not coincide with the center of gravity, which causes coupling between bending and torsion, which means that if there is bending, there will simultaneously be torsion and vice versa, which requires computing the torsional moment and the tangential stresses in order to estimate the maximum stress.

In the case of parts with deviated bending, that is, parts with bending in a direction that does not coincide with the main axes of inertia, the stress can be estimated by decomposing the bending moment according to the main axes of inertia. If in addition the center of shear coincides with the center of gravity and the warping of the section can be neglected, we can estimate the maximum stress as:.

Where:.

When there is also torsion "Torsion (engineering)") the warping is not negligible, nor are the reference axes necessarily main axes, the expression of the tension at any generic point is given by:.

Where:.